Systems and methods for improving resolution in lensless imaging
An infrared imaging system includes a phase grating overlying a two-dimensional array of thermally sensitive pixels. The phase grating comprises a two-dimensional array of identical subgratings that define a system of Cartesian coordinates. The subgrating and pixel arrays are sized and oriented such that the pixels are evenly distributed with respect to the row and column intersections of the subgratings. The location of each pixel thus maps to a unique location beneath a virtual archetypical subgrating.
1. An imaging device comprising:
an optical phase grating layer including a repeating pattern of subgratings, with a first subgrating number gx of the subgratings along a first axis X and a second subgrating number gy of the subgratings along a second axis Y; and
a pixel array having pixels, including:
a first pixel number px of the pixels along the first axis X, the first pixel number px coprime with the first subgrating number gx in that the first pixel number px and the first subgrating number gx share no common integer factor other than one; and
second pixel number py of the pixels along the second axis Y, the second pixel number py coprime with the second subgrating number gy in that the second pixel number py and the second subgrating number gy share no common integer factor other than one.
2. The imaging device of claim 1 , wherein the repeating pattern of the subgratings comprises rows and columns of the subgratings.
3. The imaging device of claim 2 , wherein the pixel array comprises rows and columns of the pixels.
4. The imaging device of claim 3 , wherein the columns of the subgratings extend at an angle with respect to the columns of the pixels.
5. The imaging device of claim 4 , wherein the angle is of a Pythagorean triple.
6. The imaging device of claim 1 , wherein the subgratings are identical.
7. The imaging device of claim 1 , the phase grating to cast an interference pattern on the pixel array, each subgrating including boundaries of odd symmetry separating stepped features on opposite sides of each boundary, the stepped features on the opposite sides of each boundary offset from the pixel array to induce a phase difference of half of a wavelength within the infrared spectrum, plus an integer multiple of the wavelength, to produce curtains of destructive interference at the pixel array.
8. The imaging device of claim 1 , further comprising superfluous pixels.
9. The imaging device of claim 8 , wherein the superfluous pixels comprise defective pixels.
10. The imaging device of claim 1 , wherein each of the pixels is located beneath a respective subgrating at a location relative to the respective subgrating, the pixel array further comprising redundant pixels at the locations relative to others of the subgratings.